CN112185268B - Image display element - Google Patents
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- CN112185268B CN112185268B CN202010627945.1A CN202010627945A CN112185268B CN 112185268 B CN112185268 B CN 112185268B CN 202010627945 A CN202010627945 A CN 202010627945A CN 112185268 B CN112185268 B CN 112185268B
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- G09F—DISPLAYING; ADVERTISING; SIGNS; LABELS OR NAME-PLATES; SEALS
- G09F9/00—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements
- G09F9/30—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements in which the desired character or characters are formed by combining individual elements
- G09F9/33—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements in which the desired character or characters are formed by combining individual elements being semiconductor devices, e.g. diodes
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- H01L25/03—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof all the devices being of a type provided for in the same subgroup of groups H01L27/00 - H01L33/00, or in a single subclass of H10K, H10N, e.g. assemblies of rectifier diodes
- H01L25/04—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof all the devices being of a type provided for in the same subgroup of groups H01L27/00 - H01L33/00, or in a single subclass of H10K, H10N, e.g. assemblies of rectifier diodes the devices not having separate containers
- H01L25/075—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof all the devices being of a type provided for in the same subgroup of groups H01L27/00 - H01L33/00, or in a single subclass of H10K, H10N, e.g. assemblies of rectifier diodes the devices not having separate containers the devices being of a type provided for in group H01L33/00
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- H01L27/12—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components specially adapted for rectifying, oscillating, amplifying or switching and having potential barriers; including integrated passive circuit elements having potential barriers the substrate being other than a semiconductor body, e.g. an insulating body
- H01L27/1214—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components specially adapted for rectifying, oscillating, amplifying or switching and having potential barriers; including integrated passive circuit elements having potential barriers the substrate being other than a semiconductor body, e.g. an insulating body comprising a plurality of TFTs formed on a non-semiconducting substrate, e.g. driving circuits for AMLCDs
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- H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
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- H01L33/48—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
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- H10K50/11—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers
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- H10K50/856—Arrangements for extracting light from the devices comprising reflective means
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- H01L25/167—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof the devices being of types provided for in two or more different main groups of groups H01L27/00 - H01L33/00, or in a single subclass of H10K, H10N, e.g. forming hybrid circuits comprising optoelectronic devices, e.g. LED, photodiodes
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Abstract
An image display element according to an aspect includes: the light emitting device includes a driving circuit board including a driving circuit for supplying current to the micro light emitting element and emitting light, the micro light emitting element, a micro lens in contact with a light emitting surface of the micro light emitting element, and a partition wall disposed around the micro lens in a direction parallel to the light emitting surface, a side surface of the partition wall facing the micro lens being a reflecting surface inclined so as to be opened with respect to a light emitting direction and reflecting light.
Description
Technical Field
The present invention relates to an image display element including a plurality of micro light emitting elements.
Background
An image display device has been proposed in which a plurality of micro light emitting elements constituting pixels are arranged on a drive circuit board (driving circuit substrate). For example, in the technique disclosed in Japanese patent application laid-open No. 2002-141492, a driving circuit is formed on a silicon substrate, and a micro light emitting diode (LED: light emitting diode) array that emits ultraviolet light is arranged on the driving circuit. In addition, in the above-described technology, a small-sized image display element that displays a color image by providing a wavelength conversion layer (wavelength conversion layer) that converts ultraviolet light into visible light of red, green, and blue on a light emitting diode array is disclosed.
Such an image Display device has characteristics of high luminance and high durability although it is small in size, and is expected to be an image Display device for a Display device such as a glasses-type terminal (Head-Up Display) or a Head-mounted Display (HUD). As a method for manufacturing such an image display element, a method is generally used in which a material of a driving circuit board and a material of a micro light emitting element are different from each other, and they are formed separately and then bonded to each other.
However, the structure of the micro light emitting element and the image display element disclosed in the above japanese patent application laid-open No. 2002-141492 has a problem that the light emitting efficiency (light emission efficiency) is low. This is mainly because the light extraction efficiency (light extraction efficiency) representing the ratio of light generated inside the body of the compound semiconductor to be emitted to the outside is low. Since the refractive index of the compound semiconductor constituting the micro light emitting element is larger than that of air or resin, total reflection occurs in a wide range of incident angles when light enters an interface between the compound semiconductor and the outside. As a result, light is confined inside the micro light emitting element, and light extraction efficiency is reduced.
In addition, the "light emission efficiency" refers to the efficiency with which current or electric power input to the micro light emitting element is converted into light emitted to the outside. Further, "light extraction efficiency" refers to the ratio of light generated in the light emitting layer of the micro light emitting element to light emitted to the outside of the micro light emitting element.
The light extraction efficiency decreases to decrease the light emission efficiency, and thus there are problems such as an increase in power consumption and an increase in temperature due to heat generation.
In addition, the micro light emitting element exhibits a light emission distribution similar to a lambertian distribution, and a light emission angle distribution is wide. For this reason, excessive light that cannot be effectively utilized in an image display element or a mobile display for a small-sized eyeglass-type terminal is emitted. As a result, power consumption increases to an unnecessary extent.
Disclosure of Invention
An aspect of the present invention has been made in view of the above-described problems, and an object of the present invention is to realize an image display element capable of enhancing light output in a front direction of a micro light emitting element by suppressing light leakage to an adjacent micro light emitting element, thereby improving light emission efficiency.
In order to solve the above-described problems, an image display element according to an aspect of the present invention is an image display element including a plurality of micro light emitting elements arranged in a plurality of arrays, comprising: the light emitting device includes a driving circuit board including a driving circuit for supplying current to the plurality of micro light emitting elements to emit light from the micro light emitting elements, the plurality of micro light emitting elements, a plurality of microlenses in contact with light emitting surfaces of the plurality of micro light emitting elements, and a plurality of partition walls arranged around the plurality of microlenses in a direction parallel to the light emitting surfaces, wherein a side surface of the plurality of partition walls facing the plurality of microlenses is a reflecting surface inclined so as to be opened with respect to a light emitting direction and reflecting light.
In order to solve the above-described problems, an image display device according to an aspect of the present invention includes a plurality of micro light emitting elements arranged in an array, and sequentially stacked: the image display device includes a driving circuit board for supplying current to the plurality of micro light emitting elements and causing the micro light emitting elements to emit light, a plurality of micro light emitting elements, and a wavelength conversion unit for extending the wavelength of excitation light emitted from the plurality of micro light emitting elements, wherein the image display element includes a plurality of partition walls arranged around the plurality of wavelength conversion units in a direction parallel to a light emitting surface of the plurality of micro light emitting elements, the plurality of wavelength conversion units are formed in a shape including a curved surface protruding in a light emitting direction, and a side surface of the plurality of partition walls facing one of the plurality of wavelength conversion units is a reflecting surface inclined so as to be opened with respect to the light emitting direction and reflecting light.
According to one aspect of the present invention, light leakage to adjacent micro light emitting elements is suppressed, and light output in the front direction of the micro light emitting elements is enhanced, whereby the effect of improving light emission efficiency is achieved.
Drawings
Fig. 1 is a schematic cross-sectional view of a pixel region of an image display element according to a first embodiment of the present invention.
Fig. 2 is a schematic plan view of a pixel region of an image display element according to a first embodiment of the present invention.
Fig. 3 is a schematic view illustrating the action of microlenses and partition walls.
Fig. 4 shows simulation results of respective light emission angle distributions in the case of the microlens and in the case of the microlens.
Fig. 5 is a schematic cross-sectional view of a pixel region of an image display element according to a second embodiment of the present invention.
Fig. 6 is a plan view of a pixel region of an image display element according to a third embodiment of the present invention.
Fig. 7 is a schematic cross-sectional view of a pixel region of an image display element according to a fourth embodiment of the present invention.
Fig. 8 is a schematic cross-sectional view of a pixel region of an image display element according to a fifth embodiment of the present invention.
Fig. 9 is a schematic cross-sectional view of a pixel region of an image display element according to a sixth embodiment of the present invention.
Fig. 10 is a schematic plan view of a pixel region of an image display element according to a sixth embodiment of the present invention.
Fig. 11 is a schematic cross-sectional view of a pixel region of an image display element according to a seventh embodiment of the present invention.
Fig. 12 is a simulation result showing the light emission distribution of the blue micro light emitting element and the light emission distribution of the red micro light emitting element according to the seventh embodiment of the present invention.
Fig. 13 is a schematic cross-sectional view of a pixel region of an image display element according to an eighth embodiment of the present invention.
Fig. 14 is a schematic cross-sectional view of an image display element according to a ninth embodiment of the present invention.
Fig. 15 is a schematic cross-sectional view of a red micro light emitting element of an image display element according to a ninth embodiment of the present invention.
Fig. 16 is a schematic cross-sectional view of a pixel region of an image display element according to a tenth embodiment of the present invention.
Fig. 17 is a schematic cross-sectional view of a pixel region of an image display element according to an eleventh embodiment of the present invention.
Fig. 18 is a schematic cross-sectional view of a pixel region of an image display element according to a twelfth embodiment of the present invention.
Fig. 19 is a schematic cross-sectional view of a pixel region of an image display element according to a thirteenth embodiment of the present invention.
Detailed Description
First embodiment
An embodiment of the present invention will be described below with reference to fig. 1 to 4 by way of example of an image display device 200 including a plurality of micro light emitting devices 100. In addition, the image display element 200 includes a plurality of micro light emitting elements 100 and a driving circuit substrate 50. The driving circuit substrate 50 controls the amount of light emission from the micro light emitting element 100 by controlling the current supplied to the micro light emitting element 100 included in the pixel region (pixel region) 1. The micro light emitting element 100 emits light in a direction (light emitting direction) opposite to the driving circuit substrate 50.
In the description of the structure of the image display element 200, unless otherwise specified, the surface on the light emitting surface (light emiting surface) 101 side is referred to as an upper surface (first surface), the surface on the opposite side to the light emitting surface 101 is referred to as a lower surface (second surface), and the surfaces on the other sides than the upper surface and the lower surface are referred to as side surfaces.
(drive Circuit Board 50)
The driving circuit board 50 is constituted by a micro light emitting element driving circuit (micro light emitting element driving circuit) that controls the current supplied to each micro light emitting element 100, a row selecting circuit that selects each row in pixels arranged in a two-dimensional array, a column signal outputting circuit that outputs a light emitting signal to each column, an image processing circuit that calculates a light emitting signal based on an input signal, an input/output circuit (driving circuit), and the like.
The surface of the driving circuit board 50 on the connection surface side to which the micro light emitting element 100 is connected is provided with a P driving electrode 51 (P-driving electrode) and an N driving electrode 52 (N-driving electrode) connected to the micro light emitting element 100. The driving circuit board 50 is typically a silicon substrate (semiconductor substrate) on which LSI (large-Scale integration) is formed, a glass substrate on which a thin film transistor (TFT: thin film transitor) is formed, or the like, and the function and structure thereof are not described in detail since they can be manufactured by a known technique.
In fig. 2, the shape of the micro light emitting element 100 as viewed from the upper surface side (light emitting surface 101 side) is schematically shown as a shape similar to a square, but the shape of the micro light emitting element 100 is not particularly limited. The shape of the micro light emitting element as viewed from the upper surface side may take various planar shapes such as a rectangle, a polygon, a circle, an ellipse, etc., but the maximum diameter (for example, the diameter thereof if circular, the diagonal thereof if rectangular) as the maximum length is assumed to be 60 μm or less. Further, it is assumed that the image display element 200 has, for example, 3000 or more micro light emitting elements 100 integrated in the pixel region 1.
(constitution of image display element 200)
As shown in fig. 2, the upper surface of the image display element 200 is a pixel region 1 in which a plurality of pixels 5 are arranged in an array. In the present embodiment, the image display element 200 is a single-color display element, and each pixel 5 includes one single-color micro light emitting element 100.
The micro light emitting element 100 includes a compound semiconductor layer 14 (compound semiconductor crystal). An N-side layer 11, a light-emitting layer (light emission layer) 12, and a P-side layer 13 are stacked on the compound semiconductor layer 14, for example. For example, in a micro light emitting element that emits light in a wavelength band from ultraviolet to green, the compound semiconductor layer 14 is an AlInGaN nitride semiconductor, and in the case of emitting light in a wavelength band from yellow to red, the compound semiconductor layer 14 is an AlInGaP semiconductor. In addition, when light is emitted in a wavelength band from red to infrared, an AlGaAs-based or GaAs-based semiconductor is used.
In the present embodiment, the structure in which the N-side layer 11 is arranged on the light emission direction side in the compound semiconductor layer 14 constituting the micro light emitting element 100 is described, but the P-side layer 13 may be arranged on the light emission direction side. Typically comprising a plurality of N-side layers 11, light emitting layers 12 and P-side layers 13 instead of a single N-side layer 11, light emitting layers 12 and P-side layers 13, and each configured to be functionally optimized, the detailed structure of each layer is not described here since it is not directly related to the nature of the present invention.
Typically, the light emitting layer 12 is sandwiched between an N-type layer and a P-type layer, but there are also cases where the N-type layer, the P-type layer contain an undoped layer, and, as the case may be, a layer containing dopants having opposite conductivities. Therefore, in this specification, the semiconductor layer on the side including the N-type layer is referred to as an N-side layer 11, and the semiconductor layer on the side including the P-type layer is referred to as a P-side layer 13, with respect to the two layers sandwiching the light-emitting layer 12. In addition, in the GaN-based compound semiconductor, si is generally used as an N-type dopant contained in the N-type layer, and Mg is generally used as a P-type dopant contained in the P-type layer.
The case of adding a dopant of "opposite conductivity" to the N-side layer 11 or the P-side layer 13 corresponds to, for example, the case of adding Si to a part of the P-type layer. That is, the P-type layer as a whole, but a part of the P-type layer contains an N-type dopant at a low concentration, and the like.
A schematic cross-sectional view of the line A-A shown in fig. 2 is shown in fig. 1. As shown in fig. 1 and 2, the micro light emitting elements 100 are arranged in a two-dimensional array on the driving circuit substrate 50. The P electrode 23P (P-type electrode) and the N electrode 23N (N-type electrode) of the micro light emitting element 100 are formed on the lower surface side of the micro light emitting element 100.
The P electrode 23P is connected to a P driving electrode 51 formed on the driving circuit substrate 50. The N electrode 23N is connected to an N driving electrode 52 formed on the driving circuit board 50. The current supplied from the driving circuit board 50 to the micro light emitting element 100 is transmitted from the P driving electrode 51 to the P side layer 13 via the P electrode 23P. The current passing through the light emitting layer 12 from the P-side layer 13 flows from the N-side layer 11 to the N-driving electrode 52 through the N-electrode 23N. In this way, the micro light emitting element 100 emits light with a predetermined intensity according to the amount of current supplied from the driving circuit substrate 50.
The individual micro light emitting elements 100 are covered with an insulating embedding material 60 and are electrically isolated from each other. In the case where the embedding material 60 is made of a material having high light transmittance such as transparency, a part of the embedding material 60 may cover the light emitting surface 101. In this case, since the embedding material 60 does not have a light shielding function, it is preferable to cover the side walls of the micro light emitting elements 100 with a metal film or the like having low light transmittance in order to suppress light leakage between the micro light emitting elements 100.
On the other hand, in order to suppress light leakage to the adjacent micro light emitting element 100, when the embedding material 60 is made of a material having low light transmittance such as a light shielding function by reflecting or absorbing light, the embedding material 60 does not preferably cover the light emitting surface 101. Therefore, the height of the light emitting surface 101 is preferably substantially equal to the height of the embedding material 60. According to this structure, since the embedding material 60 does not interfere with the light emitting surface 101 of the micro light emitting element 100, the light emission of the micro light emitting element 100 is not hindered.
The microlens 40 has a shape including a surface having a flat bottom surface as a surface on a side contacting the light emitting surface 101 and a curved surface protruding in a light emitting direction as a surface on the outer side. As such a shape, for example, a spherical surface, a revolution ellipsoidal surface, or the like, a so-called hemispherical shape can be exemplified. In the present embodiment, the surface of the microlens 40 is a hemispherical curved surface portion. The microlens 40 is filled with a material such as a transparent resin having high light transmittance. That is, the microlens 40 is configured as a convex lens. The bottom surface of the microlens 40 is substantially circular, and the center thereof preferably overlaps the center of the light emitting surface 101, but may have the same shape as the light emitting surface if there is an area limitation. Specifically, the surface of the microlens 40 is a spherical surface, and the center of the spherical surface is preferably located within ±1 μm with respect to the center of the light emitting surface 101.
The bottom surface of the microlens 40 is preferably in contact with the light emitting surface 101 of the micro light emitting element 100, but may be in contact with a thin transparent film. In addition, the bottom surface of the microlens 40 preferably entirely covers the entire light emitting surface 101. The microlens 40 may be formed into a lens shape by, for example, forming a transparent resin pattern by photolithography, and then subjecting the transparent resin to heat treatment to fluidize the transparent resin. Alternatively, the microlens 40 may be formed by pressing a mold processed into a microlens array shape against the driving circuit board 50 coated with the transparent resin.
A partition wall 34 is provided around the microlens 40 in a direction parallel to the light emitting surface 101. The reflecting surface 34S of the partition wall 34 is inclined at an inclination angle θw so as to open in the light emission direction. In the present embodiment, the reflecting surface 34S is formed around the microlens 40 by forming the partition wall 34 with a material (for example, a metal material) having a high reflectance. That is, the microlenses 40 are provided independently for each pixel, and adjacent microlenses 40 are separated from each other by the partition wall 34.
Examples of the material having high reflectivity include silver and aluminum. The partition wall 34 may also be formed in a shape that the side wall is opened in the light emitting direction to be inclined by depositing a metal thin film and performing taper etching using a photolithography technique and a dry etching technique. Alternatively, the metal pattern inclined to the side surface of the partition wall 34 may be directly formed by a lift-off method. In the present embodiment, as shown in fig. 2, the reflecting surface 34S is kept at a certain distance from the surface of the microlens 40. In addition, it is preferable that the reflecting surface 34S and the microlens 40 are not in contact, but the bottom of the partition wall 34 and the bottom of the microlens 40 are allowed to be in contact to reduce the area of the pixel 5.
According to the image display element 200 described above, the partition wall 34 is disposed around the microlenses 40. For this reason, light leakage to the adjacent micro light emitting element 100 can be suppressed. In addition, according to the image display element 200, the side surface of the partition wall 34 facing the microlens 40 is a reflection surface 34S inclined so as to open in the light emission direction. For this reason, the light path of the light emitted from the microlens 40 and traveling toward the partition wall 34 is reflected by the reflection surface 34S, and is changed to a direction along the front direction (center line direction) of the micro light emitting element 100. For this reason, since the light output in the front direction of the micro light emitting element 100 is enhanced, the luminance in the front direction of the micro light emitting element 100 can be improved.
The effects of the microlens 40 and the reflection surface 34S will be described with reference to fig. 3 and 4. The graph 401 of fig. 4 shows a difference in light emission distribution of light emitted from the micro light emitting element 100 according to the presence or absence of the micro lens 40 (shown after integration of light intensity with respect to the direction toward the azimuth angle).
As shown in fig. 3, the light Emission angle (Emission angle) is an angle with respect to the center line of the microlens 40. In addition, since the light emission distribution is difficult to measure, the light emission distribution of the light emitted from the micro light emitting element 100 is found by the ray tracing simulation. As shown in graph 401 of fig. 4, the light output from the micro light emitting element 100 increases by a maximum of about 2.5 times in some cases, as compared to the case without the micro lens 40. Here, it can be seen that the increased light is mostly in the region where the light emission angle is 30 degrees or more.
However, this is not useful since light of a large light exit angle cannot pass from the front to an observer who views the image display element 200. In addition, as in a glasses type terminal or HUD (head mounted display), even when light emitted from the micro light emitting element 100 through a lens or the like is condensed and an image formed by the image display element 200 is projected onto a screen or the like, the light condensing range of the lens is not large (for example, 40 degrees or less), so that light at a large emission angle is not useful.
The graphs 402 and 403 of fig. 4 are graphs showing where light of an emission angle of 60 degrees or more, which is significantly increased in the light emission amount, is emitted from the microlens 40 in the presence of the microlens 40. The graph 402 of fig. 4 is a distribution of height positions (Z) from the bottom surface of the microlens 40, and the graph 403 of fig. 4 is a distribution of distances (Ra) from the center of the microlens 40.
As can be seen from the graphs 402 and 403 of fig. 4, the light having a large light exit angle Z is nearly 0 μm, that is, mainly emitted from the vicinity of the outer periphery of the microlens 40.
As a result, it was revealed that by providing the microlenses 40, the light emitted from the light emitting surface 101 of the micro light emitting element 100 in the direction of the adjacent micro light emitting element 100 increases. Such light is reflected by the microlenses 40 of the adjacent micro light-emitting elements 100, and appears as if emitted from the adjacent pixels. That is, by providing the microlenses 40, there is a risk of deterioration of light leakage between adjacent micro light emitting elements 100. Here, by providing the partition wall 34 on the outer periphery of the microlens 40, light emitted in the direction of the thus-adjacent micro light emitting element 100 can be cut off. Therefore, the problem of light leakage does not occur. Further, as shown in fig. 3, light emitted at a large emission angle α is reflected in the front direction of the micro light emitting element 100, so that it can be effectively utilized. In addition, the emission angle α is an angle corresponding to the center line direction and the direction in which light is emitted.
At the outer peripheral portion of the microlens 40, light emitted from the height Z at the emission angle α is reflected to the center line at an angle of 2xθw+α -pi (pi radian=180 degrees) by the reflection surface 34S of the inclination angle θw. I.e. the emission angle is converted from alpha to 2 x theta w + alpha pi. For example, θw=52.5 degrees in order to reflect light emitted at α=75 degrees toward the center line. At this time, light having α of 60 degrees to 90 degrees becomes light emitted at a new emission angle of 0 degrees to 15 degrees through the reflection surface 34S. For reflecting light emitted at α=60 degrees toward the center line, θw=60 degrees. At this time, light having α of 60 degrees to 90 degrees becomes light emitted at a new emission angle of 0 degrees to 30 degrees through the reflection surface 34S. Further, θw is not limited to this, and is, for example, greater than 45 degrees, and is generally preferably 45 degrees or more and 60 degrees or less.
As shown in fig. 3, if the distance from the end of the microlens 40 to the end of the bottom of the reflecting surface 34S is set to D, the height Zh at which the light emitted from the height Z at the emission angle α is located on the reflecting surface 34S is represented by the following formula (1).
Zh＝{Z+(D+1/2×Z 2 /R)}/{1-1/(tanθw×tanα)} (1)
R is the radius of curvature of the hemispherical surface of the microlens 40. The larger D is, the larger Zh is, so that the height of the partition wall 34 needs to be increased. Therefore, in order to facilitate the manufacture of the image display element 200, the smaller D is, the better. That is, it is desirable that the distance from the end of the microlens 40 to the end of the bottom of the reflecting surface 34S is as small as possible. If this condition is satisfied and Z/R is also less than 1.0, zh can be approximated by simplifying equation (1) in such a way that Zh.about.Z/{ 1-1/(tan. Theta. W. Times.tan. Alpha.) }.
In the example of fig. 3, z=2 μm, θw=45 degrees, α=60 degrees, then zh=4.7 μm. This is because the height of the partition wall 34 with respect to the center line direction is generally lower than the height of the microlens 40 with respect to the center line direction. That is, it can be said that the height of the partition wall 34 with respect to the center line direction is sufficient to be equal to or less than the height of the microlenses 40 with respect to the center line direction.
Here, the emission angle distribution of the light emission amount when θw=60 degrees, d=0, and the height of the partition wall 34 is equal to R (=5.8 μm) was simulated. As shown in the graph 404 of fig. 4, it can be seen that in the case where the reflecting surface 34S of the partition wall 34 is present, the distribution is shifted in the direction of the light emission angle smaller than in the case where it is absent.
Further, the simulation of the light extraction efficiency was performed by changing the magnitude of θw and the height of the partition wall 34. In the graph 405 of fig. 4, the dependence of the light extraction efficiency on θw when the height of the partition wall 34 is equal to R is shown. The emission efficiency (total emission amount) of the total emission light irrespective of the emission angle and the emission efficiency (emission angle 40 degrees or less) of the light having an emission angle of 40 degrees or less are shown. The light extraction efficiency of light having an emission angle of 40 degrees or less is an index of the degree of concentration of the observation light in the front direction. As shown in the graph 405 of fig. 4, if θw is in the range of 45 degrees to 70 degrees, more than half of the total emitted light can be concentrated in the range of the radiation angle 40 or less.
Further, the graph 406 of fig. 4 shows the dependence of the light extraction efficiency on the height of the partition wall 34 (θw=60 degrees). The higher the partition wall 34 is, the higher the extraction efficiency of light having an emission angle of 40 degrees or less is. However, the partition wall 34 cannot be raised arbitrarily. As shown in fig. 3, if the partition wall 34 is raised, the width of the bottom of the partition wall 34 increases, and the size of the light emitting surface is restricted. Therefore, the height of the partition wall 34 is preferably about the height of the microlens 40.
As described above, by providing the microlens 40 so as to cover the light emitting surface 101 of the micro light emitting element 100, the light output can be greatly improved, and further, by providing the partition wall 34 having an inclined reflecting surface so as to open in the light emitting direction around the microlens 40, the light leakage of the adjacent micro light emitting element 100 can be suppressed, and at the same time, the light emitted in the center line direction can be increased, and therefore, the light utilization efficiency can be improved.
Second embodiment
Another embodiment of the present invention will be described below with reference to fig. 5. For convenience of explanation, members having the same functions as those described in the above embodiments are given the same reference numerals, and the explanation thereof will not be repeated. The same applies to the third embodiment.
In the image display element 200a according to the present embodiment, the structure of the partition wall 34a is different from that of the image display element 200 of the first embodiment. In this embodiment mode, it is intended to realize an image display element having pixels larger than those of the first embodiment mode. In the first embodiment, the micro light emitting element 100 is covered with the embedding material 60, and the partition wall 34 is provided thereon. However, in the present embodiment, the partition wall 34a is directly provided on the driving circuit board 50 without using the embedding material 60. This form may be adopted when the pixel pitch is large and the space between the micro light emitting elements 100 is large.
In addition, the partition wall 34a is formed to have a height equal to that of the microlens 40 a. The height of the partition wall 34a is not limited to this, and may be smaller than the height of the microlens 40a if the height is higher than the position of the bottom surface of the microlens 40 a. Therefore, the height of the partition wall 34a is higher than that of the partition wall 34 of the first embodiment, and therefore the partition wall 34a formed by molding in advance can be bonded to the drive circuit board 50. In the present embodiment, the partition wall 34a achieves the same light shielding effect as the buried material 60. Therefore, in the present embodiment, the same effects as those of the first embodiment can be achieved.
Third embodiment
Another embodiment of the present invention will be described below with reference to fig. 6. In the image display element 200b of the present embodiment, the shape of the partition wall 34b is different from that of the image display element 200 of the first embodiment. In the first embodiment, the planar shape of the microlens 40 is circular, and the reflecting surface 34S is also formed in a circular shape at a distance from the surface of the microlens 40. However, as shown in fig. 6, the partition wall 34b may be in a shape in which the surface of the reflection surface 34Sb is parallel to the sides of the rectangular pixels 5. In other words, the cross-sectional shape of the partition wall 34b as viewed from the light emitting surface 101 side of the micro light emitting element 100 may be rectangular. In the present embodiment, the same effects as those of the first embodiment can be achieved. In addition, the present structure has an advantage of easy formation of the partition wall 34.
Fourth embodiment
Another embodiment of the present invention will be described below with reference to fig. 7. In the image display element 200c of the present embodiment, the constitution of the partition wall 34c is different from that of the image display element 200 of the first embodiment.
As shown in fig. 7, the partition wall 34c of the present embodiment includes a partition wall base material 35 and a partition wall reflecting material 36. In the partition wall 34c, the surface of the partition wall reflective material 36 formed on the side of the partition wall 34c facing the microlens 40 is the reflective surface 34Sc. When the thickness of the partition wall reflecting material 36 is substantially constant over the entire side surface, the inclination angle θw of the reflecting surface 34Sc is substantially equal to the inclination angle of the side surface of the partition wall base material 35. The partition wall base material 35 may be made of, for example, siO 2 Inorganic materials such as SiN, and resin materials such as photoresist materials. The partition wall reflecting material 36 may be constituted of, for example, a highly reflective metal film or the like. In addition, in the case of the optical fiber,if the reflecting surface 34Sc is a surface capable of reflecting light satisfactorily, the partition wall 34c may be constituted by a plurality of members.
As shown in the first embodiment, when an attempt is made to construct the partition wall 34 by a single reflective material, it is necessary to deposit a metal film higher than the height of the partition wall 34 during the manufacturing process, and then process into the shape of the partition wall 34 having inclined surfaces by photolithography and dry etching techniques. Since the height of the partition wall 34 is sometimes several μm, it is necessary to deposit a very thick metal film, but the surface irregularities of such a thick metal film are large, and it is difficult to precisely align the underlayer (the buried material 60 in the present embodiment) of the metal film. Further, since the bottom of the reflection surface 34S is desirably not covered with the light emitting surface 101 of the micro light emitting element 100, as the pixel size of the pixel 5 included in the image display element 200c becomes smaller, the necessity of precisely aligning the partition wall 34 with the light emitting surface 101 increases. Therefore, the present embodiment aims to avoid the above-described problem by forming the center portion of the partition wall 34c (the partition wall base material 35) from a material that is easily precisely aligned, has few surface irregularities and is transparent, and covering the surface with the partition wall reflective material 36.
An opening 37 is formed in the partition wall reflection material 36. The opening 37 is preferably formed to cover the entire light emitting surface 101. That is, the partition wall reflecting material 36 preferably does not overlap the light emitting surface 101. The bottom of the microlens 40 preferably covers the entire surface of the opening 37. In the present embodiment, the same effects as those of the first embodiment can be achieved.
Fifth embodiment
Another embodiment of the present invention will be described below with reference to fig. 8. The image display element 200d of the present embodiment is different from the micro light emitting element 100 of the first embodiment in the micro light emitting element 100 d. That is, in the compound semiconductor layer 14, the P electrode 23P and the N electrode 23N are provided on the lower surface side of the micro light emitting element 100 bonded to the driving circuit board 50, but the micro light emitting element 100d has the P electrode 23Pd (lower electrode, first electrode) provided on the lower surface side of the compound semiconductor layer 14 and the common N electrode 30 (upper electrode, second electrode) provided on the light emitting surface 101 side of the compound semiconductor layer 14. In this structure, since the N-type electrode does not need to be provided on the lower surface side of the compound semiconductor layer 14, there is an advantage that the micro light emitting element 100d can be easily made finer. The P electrode 23Pd (first electrode) is provided for each of the micro light emitting elements 100d, and the common N electrode 30 (second electrode) is provided so as to be connected (across) the micro light emitting elements 100 d. In the case where the P-side layer 13 is disposed on the light emission direction side, the first electrode serves as an N electrode and the second electrode serves as a P electrode.
In the image display element 200d, the common N electrode 30 is connected to the N driving electrode 52 on the driving circuit substrate 50d outside the pixel region 1. Here, the connection method is not directly related to the essence of the present invention, and is not shown. The P electrode 23Pd is connected to the P drive electrode 51d on the drive circuit board 50 d. The current supplied from the driving circuit board 50d to the micro light emitting element 100d is transmitted from the P driving electrode 51d to the P side layer 13 via the P electrode 23 Pd. The current passing through the light emitting layer 12 from the P-side layer 13 flows from the N-side layer 11 to the N-driving electrode 52 via the common N-electrode 30. In this way, the micro light emitting element 100d emits light with a predetermined intensity according to the amount of current supplied from the driving circuit substrate 50 d.
As with the micro light emitting element 100 of the first embodiment, each micro light emitting element 100d is electrically isolated by the embedding material 60. In particular, in the micro light emitting element 100d, the side surface of the periphery of the light emitting layer 12 is formed as an inclined surface, and the inclined surface opens in the light emitting direction of about 30 degrees to 60 degrees. In this way, by tilting the side surface of the periphery of the light emitting layer 12 open in the light emitting direction, the light extraction efficiency from the micro light emitting element 100d can be improved. The inclined portion formed on the surface opposite to the light emitting surface 101d of the micro light emitting element 100d is covered with a protective film 17 as a transparent insulating film. The opposite side of the protective film 17 to the compound semiconductor layer 14 is preferably covered with a highly reflective metal film.
In general, the common N electrode 30 is often formed of a transparent conductive film, but in the present embodiment, the partition wall reflecting material 36 shown in the fourth embodiment is used as the common N electrode 30. The reflecting surface 34Sc of the partition wall 34c needs to be a surface that reflects light satisfactorily, and in many cases, a metal film such as silver or aluminum is used in part. By using the constituent material of the partition wall 34c as the common N electrode 30 in this manner, the manufacturing process can be simplified. The partition wall reflecting material 36 adjoins the N-side layer 11 in the light emitting surface 101 d. That is, the opening 37 formed in the partition wall reflecting material 36 is not provided in the entire light emitting surface 101d, but is provided inside the light emitting surface 101 d. The structure of the microlens 40 is the same as that of the fourth embodiment. In the present embodiment, the same effects as those of the first embodiment can be achieved.
Sixth embodiment
Another embodiment of the present invention will be described below with reference to fig. 9 and 10. The schematic cross-sectional view of section A-A of fig. 10 is that of fig. 9. The image display element 200e of the present embodiment is a full-color display element of three primary colors of RGB, and the pixel 5 includes a blue subpixel 6, a red subpixel 7, and a green subpixel 8. As shown in fig. 10, the blue subpixel 6 includes a blue micro light emitting element (micro light emitting element) 100B, and the red subpixel 7 includes a red micro light emitting element (micro light emitting element) 100R. Further, as shown in fig. 10, the pixel 5 includes two green sub-pixels 8 including one green micro light emitting element (micro light emitting element) 100G.
The red micro light emitting element 100R is constituted by a blue micro LED (micro LED) 105 that emits blue light and a red wavelength converting portion (wavelength converting portion) 32. Similarly, the green micro light emitting element 100G is composed of a blue micro LED105 and a green wavelength conversion section (wavelength conversion section) 33. The blue micro light emitting element 100B is constituted by the blue micro LED105 and the transparent portion 31.
The blue micro LED105 is the same as the micro light emitting element 100 of the first embodiment. The light emitting surface 101B of the blue micro light emitting element 100B is the upper surface of the transparent portion 31. The light emitting surface 101R of the red micro light emitting element 100R is the upper surface of the red wavelength converting region 32, and the light emitting surface 101G of the green micro light emitting element 100G is the upper surface of the green wavelength converting region 33. In this configuration, a wavelength conversion unit for performing wavelength down-conversion is provided for red and green light, using blue light as excitation light, and the excitation light is directly used for blue light. In addition, down-conversion herein means extending the wavelength of the excitation light (reducing the energy of the light).
However, near ultraviolet rays and ultraviolet rays may be used as excitation light, and the excitation light may be down-converted to generate blue light. In the following description, the transparent portion 31, the red wavelength converting portion 32, and the green wavelength converting portion 33 are described as wavelength converting portions only, unless otherwise specified.
The blue micro light emitting element 100B, the red micro light emitting element 100R, and the green micro light emitting element 100G are covered with the embedding material 60e in the periphery other than the light emitting direction side, as in the first embodiment. That is, not only the blue micro LED105 but also the transparent portion 31, the red wavelength conversion portion 32, and the green wavelength conversion portion 33 are covered with the embedding material 60e around the outside of the light emission direction side.
The microlens 40 and the partition wall 34c are the same as those of the fourth embodiment shown in fig. 7. The difference from fig. 7 is that light emitting surfaces 101B, 101R, and 101G are located on the upper surfaces of the transparent portion 31, the red wavelength converting portion 32, and the green wavelength converting portion 33, respectively. In the present embodiment, the same effects as those of the first embodiment can be achieved. In addition, this embodiment has an advantage that full-color display with high luminance can be realized by one image display element 200e by using a nitride semiconductor with high light emission efficiency and good durability.
Seventh embodiment
Another embodiment of the present invention will be described below with reference to fig. 11 and 12. The image display element 200f of the present embodiment is the same full-color display element as the image display element 200e of the sixth embodiment. The difference from the image display element 200e is the shape and the configuration of the blue micro LED105f generating the excitation light, and the shapes of the transparent portion 31, the red wavelength converting portion (wavelength converting portion) 32, and the green wavelength converting portion (wavelength converting portion) 33.
In order to improve the light extraction efficiency of the blue micro LED105f generating excitation light, the side surface 16S around the light emitting layer 12 is opened in the light emission direction so as to be inclined at an angle of 30 degrees or more and 60 degrees or less with respect to the light emitting layer 12, and the side surface 11S of the N-side layer 11 is also inclined at an angle θb of 70 degrees or more and 85 degrees or less with respect to the common N electrode 30. The inclined surfaces have high light transmittance, and for example, by covering the compound semiconductor with a transparent insulating film and covering the outside of the insulating film with a highly reflective metal film such as aluminum or silver, the light extraction efficiency can be further improved.
As shown in fig. 11, in the image display element 200f, the light-emitting layer 12 and the P-side layer 13 are disposed on the driving circuit board 50d side, the P electrode 23P (first electrode) is disposed on the driving circuit board 50d side, and the common N electrode 30 (second electrode) is disposed on the light-emitting surface side. However, even if the shape of the blue micro LED105f from the image display element 200f is not changed, and the P-side layer 13 and the light emitting layer 12 are arranged on the light emitting surface side, the same effect as that of the image display element 200f can be obtained. In this case, the first electrode is an N electrode and the second electrode is a common P electrode. In addition, the polarity of the driving electrode of the driving circuit substrate 50d is also reversed.
The side walls of the transparent portion 31, the red wavelength converting portion 32, and the green wavelength converting portion 33 are also opened in the light emission direction, and are preferably inclined at an angle θs of 45 degrees or more and 85 degrees or less with respect to the common N electrode 30.
By tilting the side wall of the wavelength converting region with respect to the light emission direction, the light extraction efficiency from the wavelength converting region can be improved. In addition, by tilting the side wall of the transparent portion 31 to be opened with respect to the light emission direction, the light extraction efficiency from the transparent portion 31 can be improved.
Further, the side walls of the transparent portion 31, the red wavelength converting portion 32, and the green wavelength converting portion 33 are also covered with a highly reflective metal film, whereby the light extraction efficiency can be further improved.
In the present embodiment, a transparent conductive film is used as the common N electrode 30. In such a configuration, after the blue micro LED105f of the excitation light source is attached to the driving circuit board 50d, the embedded material 60 is formed, and the common N electrode 30 is formed thereon. Thereafter, the transparent portion 31, the red wavelength converting region 32, the green wavelength converting region 33, and the buried material 61 covering these wavelength converting regions are formed.
In this embodiment, fig. 12 shows a simulation result of the light emission angle distribution of blue light and red light. Graph 1201 of fig. 12 shows a comparison of the case with and without microlenses 40 for blue light. Graph 1202 of fig. 12 shows a comparison of the case with the microlens 40 for red light and the case without. In either of the blue light and the red light, as shown in tables 1 and 2 below, respectively, in the case where the microlens 40 is present, the light emission amount (external emission in tables 1 and 2) is greatly increased as compared with the case where the microlens 40 is not present. Especially red light, the light emission is greatly improved by about 2 times.
TABLE 1
| With micro-lenses | Microlens-free | |
| Loss of compound semiconductor layer | 25.2％ | 37.2％ |
| Loss of transparent part | 5.8％ | 15.6％ |
| Loss in lens | 6.4％ | 0％ |
| External exit | 62.3％ | 46.4％ |
| Totalizing | 99.8％ | 99.2％ |
TABLE 2
| With micro-lenses | Microlens-free | |
| Loss of compound semiconductor layer | 14.6％ | 31.4％ |
| Red wavelength conversion loss | 14.6％ | 35.2％ |
| Loss in lens | 4.2％ | 0％ |
| External exit | 66.4％ | 32.8％ |
| Totalizing | 99.8％ | 99.4％ |
However, the light emission angle distribution is greatly different in the effect of the microlens 40 in the case of directly emitting excitation light to blue light outside the blue subpixel 6 and in the case of producing red light in the red wavelength converting region 32 f. In the case of blue light, the light emitted from the microlens 40 in the range of 20 degrees or more and 60 degrees or less is increased, but in the case of red light, the light emission amount is greatly increased around the light emission angle of 70 degrees. The distribution diagram 1203 of fig. 12 shows the emission position distribution of the red light emitted during the period in which the light emission angle is 65 degrees or more and 75 degrees or less. In this case, it can be seen that most of the red light is emitted from the outer peripheral portion of the microlens 40.
From this result, it can be easily inferred that the effect of the reflecting surface 34Sc of the partition wall 34c is greater for red light than for blue light. That is, for a full-color display element such as the image display element 200f, the shape of the partition wall 34c should be designed to exert the effect on red light to the maximum. In the example of the graph 1202 of fig. 12, since the light emitted at the light emission angle of 70 degrees is preferably parallel to the center line of the microlens 40, the inclination angle θw of the reflection surface 34Sc is preferably 55 degrees.
In the case where the reflection surface 34Sc of the above condition is provided, the light emission angular distribution is simulated. The case of blue light is shown in fig. 1204 of fig. 12, and the case of red light is shown in fig. 1205 of fig. 12. The height of the partition wall 34c is set equal to the radius of the microlens 40, d=0. Table 3 shows the amount of external emission light below 40 degrees of emission angle in blue light and red light. As shown in table 3, since the reflection surface 34Sc is provided, the external emission light increases in the region where the light emission angle is small. This effect increases by 18% in blue light and 120% in red light. In this way, the reflecting surface 34Sc can greatly increase the amount of light emitted from the micro light emitting element toward the center line direction of the micro lens 40. The same effect as that of red light can be expected for green light.
TABLE 3
| No reflecting surface | With reflecting surfaces | |
| Blue light | 25.4％ | 30.0％ |
| Red light | 16.2％ | 35.6％ |
In order to improve the luminance in the front direction of the micro light emitting element 100f, the contact angle θc of the micro lens 40 is important. As shown in fig. 3, the contact angle θc is an angle formed by the bottom of the microlens 40 and the surface of the microlens 40. Specifically, in the case where the surface of the microlens 40 is spherical, θc=90 degrees when the center of the microlens 40 overlaps the light exit surface, and θc becomes smaller as the center moves downward from the light exit surface.
Fig. 12 is a graph 1206 showing simulation results of θc dependence of light extraction efficiency at a light emission angle of 40 degrees or less and light extraction efficiency without the reflection surface 34 Sc. As θc becomes smaller, the light extraction efficiency from the microlens 40 to the outside decreases. On the other hand, although the light extraction efficiency decreases at a light emission angle of 40 degrees or less, a substantially fixed value is maintained at θc+.74 degrees. In this way, in order to improve the luminance in the front direction of the micro light emitting element, the contact angle θc is preferably kept at 74 degrees or more.
In the present embodiment, the same effects as those of the first embodiment can be achieved.
Eighth embodiment
Other embodiments of the present invention will be described below with reference to fig. 13. The image display element 200g of the present embodiment is a full-color display element similar to the image display element 200f of the seventh embodiment. Except that a wavelength converting region is disposed within the partition wall 34g and a microlens 40 is provided thereon.
As described in the seventh embodiment, by tilting the side wall of the wavelength converting region with respect to the light emission direction, the light extraction efficiency from the wavelength converting region can be improved. On the other hand, in order to reflect light emitted from the outer peripheral portion of the microlens 40 at a large light exit angle in the center line direction of the microlens 40, it is necessary to tilt the reflecting surface 34Sg of the partition wall 34g also to be opened with respect to the light emission direction. Therefore, by disposing the wavelength conversion portion in the microlens 40 in the partition wall 34g, the light extraction efficiency can be improved, and the light output of the micro light emitting element in the front direction can be enhanced, thereby improving the light emission efficiency. In this specification, the blue micro light emitting element 100Bg, the red micro light emitting element 100Rg, and the green micro light emitting element 100Gg may be collectively referred to as micro light emitting elements.
Further, as shown in fig. 13, the height of the partition wall 34g in the center line direction may be smaller than the height of the microlens 40 in the center line direction. As shown in the graph 406 of fig. 4, it can be considered that the light extraction efficiency of the light emitted in the center line direction of the microlens 40 increases as the height of the partition wall 34g increases. However, if the partition wall 34g is increased, the light exit surface is reduced. Due to the reduction of the light emitting surface, the light emitting efficiency may be lowered. In addition, the lower the partition wall 34g is, the easier the image display element is manufactured. Therefore, the optimum value of the height of the partition wall 34g can be selected in comparison with the positive effect by increasing the height of the partition wall 34g and the negative effect by narrowing the light emitting surface.
In the present embodiment, the configuration of the blue micro LED105f as an excitation light source on the driving circuit substrate 50d is the same as that of the seventh embodiment. The structure in which the partition wall base material 34Bg is disposed on the common N electrode 30 and the partition wall reflecting material (forming the reflecting surface 34 Sg) is disposed thereon is the same as that of the fourth embodiment shown in fig. 7. In fig. 7, the opening 37 of the partition wall reflecting material 36 completely covers the light emitting surface 101 of the micro light emitting element 100, but in the present embodiment, the opening 37g covers a part of the upper surface of the blue micro LED105 f. This is to suppress light leakage from the wavelength conversion portion to the driving circuit board 50d side when the embedding material 60g does not have light shielding properties. In the present embodiment, the same effects as those of the first embodiment can be achieved.
Ninth embodiment
Another embodiment of the present invention will be described below with reference to fig. 14 and 15. The image display element 200h of the present embodiment is a full-color display element similar to the image display element 200f of the seventh embodiment, but is different in that a QLED (Quantum dot light-emitting diode: quantum dot LED) is used as the micro light emitting element. In the present embodiment, the red micro light emitting element 100Rh is constituted by the P driving electrode 51d (first electrode), the red light emitting layer 110R formed thereon, and the common N electrode 30 (second electrode) formed thereon.
As shown in fig. 15, the red light emitting layer 110R is provided with an electron transport layer 121 and a hole transport layer 122 on both sides of the quantum dot layer 120. The red light emitting layer 110R emits light by injecting electrons and holes from the electron transport layer 121 and the hole transport layer 122, respectively, and recombining in the quantum dots included in the quantum dot layer 120. By varying the core size of the quantum dots, the emission wavelength can be controlled. Accordingly, the blue micro light emitting element 100Bh and the green micro light emitting element 100Gh may be constituted by QLEDs as well. Hereinafter, when it is not necessary to distinguish colors, it is sometimes referred to as the light-emitting layer 110. Since the configuration details of the QLED are not directly related to the essence of the present invention, they are not involved in the present description.
The common N electrode 30 is a transparent conductive film. The surface of the P drive electrode 51d is preferably high in reflectance to visible light. The light emitting surface in this embodiment is the surface of each of the light emitting layers 110B, 110R, and 110G. Further, by disposing the electron transport layer 121 on the driving circuit board 50d side and disposing the hole transport layer 122 on the light emitting surface side, QLEDs may be disposed with opposite polarities. In this case, the first electrode is an N electrode and the second electrode is a common P electrode.
In the example shown in fig. 4, a microlens 40 made of transparent resin is disposed on the compound semiconductor layer 14 having a refractive index of about 2.4. In a graph 1202 of fig. 12, a microlens 40 made of transparent resin is disposed on a wavelength conversion region having a refractive index of about 1.6. In either case, the microlens 40 achieves a very large improvement in light extraction efficiency. In this way, even when the refractive index of the light emitting surface greatly changes, improvement in light extraction efficiency can be achieved by the microlenses 40. Although the refractive index of the light emitting surface of the QLED cannot be accurately measured, it is assumed from the refractive index of the resin layers constituting the quantum dot material, the electron transport layer 121, and the hole transport layer 122 that there is not much difference from the examples of fig. 4 and 12. Therefore, the same effect as that of the microlens 40 can be expected in the present embodiment using the QLED.
The partition wall 34c is made of metal, and as shown in fig. 14, is in direct contact with the common N electrode 30 in the pixel, and thus can be used as a part of the N electrode wiring. In particular, in order to reduce light absorption of the common N electrode 30, the common N electrode 30 needs to be thinned, and the resistance of the common N electrode 30 increases. By using the partition wall 34c as a part of the wiring sharing the N electrode 30, an increase in resistance on the N electrode side can be suppressed. In the present embodiment, the microlens 40 is arranged to cover the light emitting surface, and further by arranging the partition wall 34c, light leakage to the adjacent micro light emitting element can be suppressed.
Modification example
As a modification of the ninth embodiment, each of the light emitting layers 110B, 110R, 110G may be replaced with an organic light-emitting diode (OLED) instead of the QLED. Like the QLED, the OLED has a structure in which a light emitting layer is disposed between an electron transport layer 121 and a hole transport layer 122.
Tenth embodiment
Another embodiment of the present invention will be described below with reference to fig. 16. The image display element 200i of the present embodiment is similar to the ninth embodiment in that a QLED is used as a micro light emitting element, but is different from the ninth embodiment in that the micro light emitting element includes a P electrode 23Pi (first electrode) having a recessed portion. In other words, the P electrode 23Pi is formed in a concave shape on the opposite side of the light emitting surface side of the micro light emitting element. The light emitting layers 110B, 110R, and 110G are disposed inside the concave portion formed on the P electrode 23 Pi. Further, by disposing the electron transport layer 121 on the driving circuit board 50d side and disposing the hole transport layer 122 on the light emitting surface side, QLEDs may be disposed with opposite polarities. In this case, the first electrode is an N electrode, the second electrode is a common P electrode, and the N electrode has a concave shape.
As shown in fig. 16, the recess side wall 23S formed on the P electrode 23Pi is inclined such that the inclination angle θq with respect to the driving circuit substrate 50d is smaller than 90 degrees. θq is preferably 30 degrees or more and 60 degrees or less. The surface of the P electrode 23Pi is formed of a highly reflective metal material.
Since the QLED is isotropically light-emitting, in fig. 16, light is also emitted in the horizontal direction. By reflecting light advancing in the horizontal direction upward, light leakage to adjacent micro light emitting elements can be suppressed, and light extraction efficiency can be improved. The light emitting layer 110 may be in contact with the sidewall 23S, but the light emitting layer 110 is preferably disposed at the bottom of the recess formed on the P electrode 23Pi, not in direct contact with the sidewall 23S. The transparent insulating film 18 is preferably disposed between the side wall of the light emitting layer 110 and the side wall 23S. In this case, since light emitted from the light-emitting layer 110 in the horizontal direction is reflected by the side wall 23S through the transparent insulating film 18 and emitted upward, the light-emitting surface 101i becomes an opening of the concave portion of the P electrode 23 Pi.
The microlens 40 is formed to cover the light emitting surface 101 i. A partition wall 34c is disposed around the microlens 40. This point is the same as the first embodiment.
In the image display element 200i, the periphery of the P electrode 23Pi in the direction parallel to the light emission surface is covered with the first insulating film 19, and the periphery of the P electrode 30 in the direction parallel to the light emission surface is covered with the second insulating film 20, which is different from the other embodiments.
The following describes a process for manufacturing the image display element 200i according to the present embodiment. The first insulating film 19 is formed on the driving circuit board 50d, and an opening is provided on the P driving electrode 51 d. The inclination angle of the opening side wall is controlled to be thetaq. A highly reflective metal thin film forming a P electrode is deposited thereon, and processed into a P electrode 23Pi forming a recess.
The first insulating film 19 may be SiO 2 Or an inorganic insulating film such as SiN, or a resin such as polyimide or silicone. The highly reflective metals as the material of the P electrode 23Pi are silver and aluminum. The light emitting layer 110 is then sequentially formed. The patterning process may be performed by directly coating the material of the light emitting layer 110, or the light emitting layer 110 formed on another substrate may be transferred onto the P electrode 23Pi. Then, the transparent insulating film 18 is formed. Further, by forming the second insulating film 20, an opening is provided in the light-emitting layer 110, and the common N electrode 30 is further formed. The transparent insulating film 18 and the second insulating film 20 are both transparent insulating films, and may be formed simultaneously. The common N electrode 30 is a transparent conductive film. The method of forming the microlenses 40 and the partition walls 34c is the same as that of the first embodiment. In the present embodiment, the microlenses 40 are also arranged so as to cover the light emitting surface 101i, and by further arranging the partition wall 34c, the same effects as those of the first embodiment can be achieved.
Eleventh embodiment
Another embodiment of the present invention will be described below with reference to fig. 17. The image display element 200j of the present embodiment is similar to the seventh embodiment shown in fig. 11, but is different in that the functions of the wavelength converting region and the microlenses are integrated.
The red micro light emitting element (micro light emitting element) 100Rj in the present embodiment is constituted by a blue micro LED (micro LED) 105f and a red wavelength converting portion (wavelength converting portion) 41 arranged on the upper surface thereof.
The red wavelength converting region 41 is similar to the microlens 40 of the other embodiments, and has a curved surface (for example, hemispherical shape) protruding in the light emission direction, but is different from the microlens 40 in that it includes a wavelength converting substance for down-converting blue light into red light.
The red wavelength converting region 41 is formed by dispersing a wavelength converting substance such as a quantum dot or a quantum rod, a fluorescent material, or a dye, which emits red light, in a transparent resin. Similarly, the green micro light emitting element 100Gj also has a hemispherical green wavelength conversion unit 42 disposed on the blue micro LED105 f. The blue micro light emitting element 100Bj has the transparent micro lenses 40 as in the other embodiments. This is because wavelength conversion of light emitted from the blue micro LED105f is not required.
A partition wall 34c is disposed around the microlens 40, the red wavelength converting region 41, and the green wavelength converting region 42. The bottom surfaces of the microlens 40, the red wavelength converting region 41, and the green wavelength converting region 42 are covered with the opening 37 of the partition wall reflecting material (forming the reflecting surface 34 Sj).
In fig. 17, the partition wall reflecting material covers a part of the light emitting surface 102 of the blue micro LED105f, but the opening 37 may completely cover the light emitting surface 102. In other words, the partition wall reflective material may not cover a portion of the light emitting surface 102. When the embedding material 60 has light-shielding properties, even if the opening 37 completely covers the light-emitting surface 102, light leakage to adjacent micro light-emitting elements is small.
The concentration distribution of the wavelength converting substance in the red wavelength converting region 41 does not necessarily have to be uniform. For example, a layer having a deep concentration of the wavelength converting substance may be disposed at the bottom of the red wavelength converting region 41, and a layer having a thin concentration of the wavelength converting substance may be disposed at the top. Alternatively, a layer having a concentration of the wavelength converting substance may be disposed in the center portion of the red wavelength converting region 41, and the concentration of the wavelength converting substance may be thinner from the center portion toward the outside. In addition, the arrangement of the concentration of the wavelength converting substance may be opposite to the above arrangement. The same applies to the green wavelength converting region 42.
In the blue micro light emitting element 100Bj, the effect of the micro lenses 40 and the partition walls 34c is the same as that of the first embodiment. In addition, the outer peripheral surface of the red wavelength converting region 41 having a hemispherical shape has an approximately vertical inclination.
In the red wavelength converting region 41, light emitted at a light emission angle in an approximately horizontal direction is easily emitted from an outer peripheral portion of the red wavelength converting region 41 having an approximately vertical inclination. Since the diameter of the outer peripheral portion of the red wavelength converting region 41 is the largest, a large amount of light is emitted at an angle in the approximately horizontal direction, and therefore a large amount of light is emitted from the outer peripheral portion at a large light emission angle, as in the seventh embodiment. Therefore, according to the present embodiment, the same effects as those of the seventh embodiment are produced. The same applies to the green micro light-emitting element 100 Gj.
As described above, the partition wall 34c disposed around the red wavelength converting region 41 (green wavelength converting region 42) in the direction parallel to the light emitting surface 102 has a shape including a curved surface protruding in the light emitting direction, and the side surface of the partition wall 34c facing the red wavelength converting region 41 (green wavelength converting region 42) is inclined to be opened with respect to the light emitting direction and serves as a reflecting surface for reflecting light. This suppresses light leakage to the adjacent micro light emitting element, and reflects light having a large light emission angle in the center line direction of the micro lens 40 or the like, thereby increasing the intensity of light emitted in the center line direction.
Twelfth embodiment
Other embodiments of the present invention will be described below with reference to fig. 18. The image display element 200k of the present embodiment is similar to the image display element 200e of the sixth embodiment shown in fig. 9, but differs in that the dielectric multilayer film 45 is disposed on the light emitting surface on which the light of the microlens 40 is emitted in the red subpixel 7 and the green subpixel 8.
By providing the microlenses 40 on the light emitting surface 101R of the micro light emitting element 100R and the light emitting surface 101G of the micro light emitting element 100G, the emission amounts of red light and green light after down-conversion increase, and as described above, the emission amount of blue light as excitation light also increases at this time.
When the absorbance (optical density) of blue light by the red wavelength converting unit 32 and the green wavelength converting unit 33 is not sufficiently large, blue light as excitation light is emitted from the red subpixel 7 and the green subpixel 8, and the color purity of red light and green light emitted from these subpixels is reduced. On the other hand, by disposing the reflective excitation light on the surface of the microlens 40, the emission of the excitation light from the red subpixel 7 or the green subpixel 8 is reduced by the dielectric multilayer film 45 transmitting the red light and the green light after down-conversion, and the color purity can be improved. In the present embodiment, the same effects as those of the first embodiment can be achieved by disposing the microlenses 40 so as to cover the light emitting surface and disposing the partition walls 34 c.
Thirteenth embodiment
Another embodiment of the present invention will be described below with reference to fig. 19. The image display element 200l of the present embodiment is similar to the image display element 200e of the sixth embodiment shown in fig. 9, but is different in that microlenses 40Y including an excitation light absorbing material including a blue light absorbing material (filter material) are disposed in place of the microlenses 40 in the red subpixel 7 and the green subpixel 8.
As described in the twelfth embodiment, there are cases where it is necessary to prevent emission of blue light (excitation light) from the red subpixel 7 and the green subpixel 8. In this case, for example, as in the case of the microlens 40Y containing the excitation light absorbing substance, by using a microlens containing a dye (filter material or the like) that absorbs blue light and does not absorb red light and green light, the emission of blue light from the red subpixel 7 and the green subpixel 8 can be reduced. In this way, even if the blue light absorbing substance is contained in the microlens 40Y containing the excitation light absorbing substance, the red light and the green light are not greatly affected, and therefore the effects of the microlens 40Y containing the excitation light absorbing substance and the partition wall 34c are not impaired. In the present embodiment, the same effects as those of the first embodiment can be achieved by disposing the microlens 40Y containing the excitation light absorbing substance so as to cover the light emitting surface and disposing the partition wall 34 c.
[ summary ]
An image display element (200) according to a first aspect of the present invention is an image display element including a plurality of micro light emitting elements (100) arranged in an array, having: a driving circuit board (50) including a driving circuit for supplying a current to the micro light emitting element and causing the micro light emitting element to emit light, the micro light emitting element, and a micro lens (40) in contact with a light emitting surface (101) of the micro light emitting element; and a partition wall (34) disposed around the microlens in a direction parallel to the light emitting surface, wherein a side surface of the partition wall facing the microlens is a reflecting surface that is inclined so as to open with respect to a light emitting direction and reflects light.
According to the above configuration, the partition wall is disposed around the microlens in the direction parallel to the light emitting surface. Therefore, light leakage to the adjacent micro light emitting element can be suppressed. In addition, according to the structure, the side surface of the partition wall facing the microlens is inclined in an open manner with respect to the light emission direction and reflects the light. Therefore, the path of the light emitted from the microlens is reflected by the reflecting surface and changed to be along the front direction of the micro light emitting element. Therefore, the light output in the front direction of the micro light emitting element is enhanced, whereby the light emitting efficiency can be improved.
The image display element (200) according to the second aspect of the present invention may preferably be in the first aspect, and the micro light emitting element (100) may be a micro LED including a compound semiconductor crystal.
In the image display element (200) according to the third aspect of the present invention, preferably, in the first aspect, the bottom surface of the microlens (40) covers the entire light emitting surface (101) of the micro light emitting element (100).
The image display element (200) according to the fourth aspect of the present invention is preferably such that, in the first aspect, the inclination angle of the reflecting surface is 85 degrees or less.
In the image display element (200) according to the fifth aspect of the present invention, preferably, in the first aspect, the surface of the microlens (40) is a spherical surface, and the center of the spherical surface is located within ±1 μm with respect to the center of the light emitting surface (101).
The image display element (200 a) according to the sixth aspect of the present invention is preferably in any one of the first to fifth aspects, and the partition wall (34 a) may be formed so as to be in contact with the surface of the driving circuit substrate (50). The above configuration can be adopted when the pixel pitch is large and the space between the micro light emitting elements is large. In addition, according to the above configuration, since the height of the partition wall is increased, the partition wall formed by molding in advance can be bonded to the driving circuit board.
In the image display element (200 b) according to the seventh aspect of the present invention, in any one of the first to sixth aspects, the shape of the partition wall (34 b) as viewed from the light emitting surface side of the micro light emitting element (100) may be rectangular.
According to an image display element (200 c) of an eighth aspect of the present invention, in any one of the first to seventh aspects, the partition wall (34 c) may include a partition wall base material (35) made of a transparent material and a partition wall reflecting material (36) covering the partition wall base material and made of a highly reflective metal film.
If the partition walls are to be formed of a single reflective material, a metal film having a height higher than that of the partition walls must be deposited, and the partition walls having inclined surfaces must be processed by photolithography and dry etching techniques. Since the height of the partition wall may be several μm, a very thick metal film is required, but such a thick metal film has a problem that the surface thereof has large irregularities and it is difficult to precisely align the base layer. Further, since the bottom of the side wall is not required to cover the light emitting surface, it is necessary to precisely align the partition wall with the light emitting surface as the pixel size of the image display element is reduced. Therefore, the above problems can be avoided by forming the partition wall base material from a transparent material that is easy to perform precise alignment and covering the surface with the partition wall reflecting material.
According to an image display element (200 d) of a ninth aspect of the present invention, in any one of the first to eighth aspects, the micro light emitting element (100 d) has a first electrode (P electrode 23 Pd) on a surface opposite to the light emitting surface, and the micro light emitting element has a second electrode (common N electrode 30) on the light emitting surface side. According to the above configuration, it is not necessary to provide the first electrode and the second electrode on the light emitting surface and the surface on the opposite side at the same time, and thus the micro light emitting element can be easily miniaturized.
According to the image display element (200 d) of the tenth aspect of the present invention, in the ninth aspect, the partition wall (34 c) may be constituted as a part of a wiring that is conductive to the second electrode (common N electrode 30). According to the above configuration, by using the partition wall as a part of the wiring sharing the N-type electrode, an increase in resistance on the N-type electrode side can be suppressed.
According to an image display element (200 e) of an eleventh aspect of the present invention, in any one of the first to tenth aspects, the micro light emitting element (100R, 100G, 100B) may have a micro LED (105) including a compound semiconductor crystal and a wavelength conversion portion (32, 33) extending a wavelength of excitation light emitted by the micro LED, and the light emitting surface of the micro LED may be an upper surface of the wavelength conversion portion.
According to an image display element (200 e) of a twelfth aspect of the present invention, in any one of the first to tenth aspects, the micro light emitting element (100 r,100g,100 b) may have a micro LED (105) including a compound semiconductor crystal and a transparent portion (31) arranged on the micro LED, and the light emitting surface of the micro LED may be an upper surface of the transparent portion.
According to an image display element (200 f) of a thirteenth aspect of the present invention, in the eleventh aspect, a surface of a side wall constituting the wavelength converting region (32 f, 33 f) in a direction parallel to the light emitting surface may be a surface inclined so as to open in a light emitting direction. By tilting the side wall of the wavelength converting region with respect to the light emission direction, the light extraction efficiency from the wavelength converting region can be improved.
According to an image display element (200 f) of a fourteenth aspect of the present invention, in the twelfth aspect, a surface of a side wall constituting the transparent portion (31 f) in a direction parallel to the light emitting surface may be a surface inclined so as to open in a light emitting direction. By tilting the side wall of the transparent portion to be opened with respect to the light emission direction, the light extraction efficiency from the transparent portion can be improved.
According to an image display element (200 f) of a fifteenth aspect of the present invention, in the eleventh or thirteenth aspect, a side wall of the wavelength converting region (32 f, 33 f) in a direction parallel to the light emitting surface may be covered with a highly reflective metal film. According to the above configuration, the light extraction efficiency of the micro light emitting element can be further improved compared to the case where the side wall of the wavelength conversion portion is not covered with the highly reflective metal film.
According to the image display element (200 f) of the sixteenth aspect of the present invention, in the twelfth or fourteenth aspect, a side wall of the transparent portion (31 f) in a direction parallel to the light emitting surface may be covered with a highly reflective metal film. According to the above structure, the light extraction efficiency of the micro light emitting element can be further improved compared to the case where the side wall of the transparent portion is not covered with the highly reflective metal film.
According to an image display element (200 g) of a seventeenth aspect of the present invention, in the eleventh, thirteenth or fifteenth aspect, the wavelength converting region (32 g, 33 g) may be disposed inside the partition wall (34 g), and the wavelength converting region and the microlens (40) may be laminated in this order.
As described above, by tilting the side wall of the wavelength converting region with respect to the light emission direction opening, the light extraction efficiency from the wavelength converting region can be improved. On the other hand, in order to reflect light emitted from the outer peripheral portion of the microlens at a large emission angle toward the center line, it is also necessary to tilt the reflecting surface of the partition wall so as to open with respect to the light emission direction. Therefore, by disposing the wavelength conversion portion and the microlens inside the partition wall, the light extraction efficiency can be improved, and the light output in the front direction of the micro light emitting element can be enhanced, and the light emission efficiency can be improved.
According to an image display element (200 g) of an eighteenth aspect of the present invention, in the eleventh aspect, the reflection surface may also cover a periphery of the wavelength conversion portion in a direction parallel to the light emitting surface.
According to the image display element (200 g) of the nineteenth aspect of the present invention, in the first aspect, a height of the reflecting surface in a center line direction may be equal to or less than a height of the microlens in the center line direction.
According to the image display element of the twentieth aspect of the present invention, in the first aspect, the micro light emitting element (100 Rh) may also have a quantum dot layer (120) containing quantum dots, and the micro light emitting element (100 Rh) is a quantum dot LED that emits light by being energized to the quantum dot layer.
According to the image display element (200 i) of the twenty-first aspect of the invention, in the first aspect, the micro light emitting element may also be an organic LED.
In the image display element (200 i) according to the twenty-second aspect of the present invention, in the ninth aspect, the first electrode (P electrode 23 Pi) may be formed in a concave shape on a side opposite to the light emitting surface side. Since the micro light emitting element emits light isotropically, it also emits light in the horizontal direction. By reflecting light advancing in the horizontal direction upward, light leakage to adjacent micro light emitting elements can be suppressed, and light extraction efficiency can be improved.
According to the image display element (200 k) of the twenty-third aspect of the present invention, in the eleventh aspect, a dielectric multilayer film (45) that reflects the excitation light and transmits the elongated light of the wavelength may be disposed on a light exit surface that emits the light of the microlens (40). According to the above structure, emission of excitation light from the micro light emitting element emitting red light and green light can be reduced, and color purity can be improved.
According to an image display element (200 l) of a twenty-fourth aspect of the present invention, in the eleventh aspect, the microlens (40Y) may also include a filter material (blue light absorption filter material) that absorbs the excitation light and transmits the elongated light of the wavelength. According to the above structure, emission of excitation light from the micro light emitting element can be reduced.
An image display element (200 j) according to a twenty-fifth aspect of the present invention is an image display element including a plurality of micro light emitting elements (100 Rj, 100Bj, 100 Gj) arranged in an array, and sequentially laminated with: and a drive circuit board (50 d) for supplying current to the micro light emitting element and causing the micro light emitting element to emit light, the micro light emitting element, and a wavelength conversion unit (50 d) for extending the wavelength of excitation light emitted from the micro light emitting element, wherein the drive circuit board has a partition wall (34 c) disposed around the wavelength conversion unit in a direction parallel to the light emitting surface of the micro light emitting element, the wavelength conversion unit is formed in a shape including a curved surface protruding in the light emitting direction, and a side surface of the partition wall facing the wavelength conversion unit is a reflection surface inclined so as to be opened with respect to the light emitting direction and reflecting light. According to the above configuration, the light output in the front direction of the micro light emitting element is enhanced, and thus the light emitting efficiency can be improved.
[ other expressions of the invention ]
The present invention can also be expressed as follows. That is, an image display element according to an aspect of the present invention is provided with: the light emitting device may further include a driving circuit board including a driving circuit for supplying current to the micro light emitting element and emitting light, the micro light emitting element arranged in an array on the driving circuit board, a micro lens arranged on a light emitting surface of the micro light emitting element, and a partition wall arranged around the micro lens, and a side surface of the partition wall facing the micro lens may be an image display element having a reflecting surface inclined so as to be opened with respect to a light emitting direction and reflecting light.
In the image display device according to one aspect of the present invention, the micro light emitting device may include a micro LED including a compound semiconductor crystal and a wavelength conversion portion for down-converting a wavelength of excitation light emitted from the micro LED, and the light emitting surface of the micro LED may be an upper surface of the wavelength conversion portion.
In the image display device according to one aspect of the present invention, the micro light emitting device may include a micro LED including a compound semiconductor crystal and a transparent portion disposed on the micro LED, and the light emitting surface of the micro LED may be an upper surface of the transparent portion.
In addition, the image display element according to an aspect of the present invention, the micro light emitting element may be a quantum dot LED that emits light by being energized to the quantum dot layer.
In addition, the image display element according to an aspect of the present invention, the micro light emitting element may be an organic LED.
In addition, an image display element according to an aspect of the present invention is provided with: the light emitting device includes a driving circuit board including a driving circuit for supplying current to the micro light emitting element and emitting light, the micro LEDs arrayed on the driving circuit board, and a wavelength conversion portion for down-converting a wavelength of excitation light emitted from the micro LEDs, wherein the wavelength conversion portion is formed in a hemispherical shape, and a side surface of the partition wall facing the wavelength conversion portion may be an image display element which is inclined so as to be opened with respect to a light emitting direction and which reflects a reflection surface of the light.
In addition, according to the image display element of an aspect of the present invention, a dielectric multilayer film that reflects the excitation light and transmits the down-converted light may be disposed on the surface of the microlens.
In addition, the microlens may also include a filter material that absorbs the excitation light and transmits the down-converted light according to an aspect of the present invention.
In the image display device according to an aspect of the present invention, the partition wall may be formed as a part of a wiring that is electrically connected to one electrode of the micro light emitting device.
In addition, according to the image display element of an aspect of the present invention, the side wall of the wavelength converting region may be inclined to be opened with respect to the light emission direction.
In the image display device according to an aspect of the present invention, the reflection surface may cover a periphery of the wavelength conversion portion.
In addition, in the image display device according to an aspect of the present invention, the inclination angle of the reflecting surface may be 85 degrees or less.
In addition, in the image display element according to an aspect of the present invention, a height of the reflection surface may be equal to or less than a middle height of the microlens.
In the image display device according to one aspect of the present invention, the microlens may cover the entire light emitting surface.
In addition, according to the image display element of an aspect of the present invention, the surface of the microlens is a spherical surface, and the center of the spherical surface may be located within ±1 μm with respect to the center of the light emitting surface.
[ additional record item ]
The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims, and embodiments in which technical means disclosed in the different embodiments are appropriately combined are also included in the technical scope of the present invention. Further, by combining the technical means disclosed in each of the embodiments, new technical features can be formed.
Claims (25)
1. An image display element comprising a plurality of micro light emitting elements arranged in an array, comprising:
a driving circuit board including a driving circuit for supplying current to the plurality of micro light emitting elements and causing the micro light emitting elements to emit light,
The plurality of micro-light emitting elements,
A plurality of microlenses in contact with the light emitting surfaces of the plurality of micro light emitting elements,
A plurality of partition walls arranged in a direction parallel to the light emitting surface and surrounding the plurality of microlenses,
the side of the partition wall facing the microlens is a reflecting surface which is inclined in such a manner as to be opened with respect to the light emission direction,
and the reflecting surface is not in contact with the surface of the microlens, and reflects light emitted from the microlens in a direction along the front direction of the micro light emitting element,
at least a portion of the partition wall is at the same height in the light emission direction as a surface of the microlens forming the curved surface.
2. The image display element according to claim 1, wherein the plurality of micro light emitting elements are a plurality of micro LEDs including a compound semiconductor crystal.
3. The image display element according to claim 1, wherein a bottom surface of the plurality of microlenses covers an entirety of the light emitting surfaces of the plurality of micro light emitting elements.
4. The image display element according to claim 1, wherein the inclination angle of the reflecting surface is 85 degrees or less.
5. The image display element according to claim 1, wherein the surface of the microlens is a spherical surface, and a center of the spherical surface is located within ±1 μm with respect to a center of the light exit surface.
6. The image display element according to any one of claims 1 to 5, wherein the partition wall is formed in contact with a surface of the driving circuit substrate.
7. The image display element according to any one of claims 1 to 5, wherein the partition wall has a rectangular shape as viewed from the light exit surface side of the micro light emitting element.
8. The image display element according to any one of claims 1 to 5, wherein the partition wall includes a partition wall base material composed of a transparent material and a partition wall reflecting material that covers the partition wall base material and is composed of a highly reflective metal film.
9. The image display element according to any one of claims 1 to 5, wherein in each of the plurality of micro light emitting elements, a first electrode is provided on a surface of the plurality of micro light emitting elements on a side opposite to the light emitting surface, and wherein in the plurality of micro light emitting elements, a second electrode is provided on the light emitting surface side of the plurality of micro light emitting elements, respectively.
10. The image display element according to claim 9, wherein the partition wall includes a portion of a wiring which is conductive to the second electrode.
11. The image display element according to any one of claims 1 to 5, wherein each of the plurality of micro light-emitting elements has a micro LED including a compound semiconductor crystal and a wavelength conversion portion extending a wavelength of excitation light emitted from the micro LED, and the light-emitting surface of the micro light-emitting element is an upper surface of the wavelength conversion portion.
12. The image display element according to any one of claims 1 to 5, wherein each of the plurality of micro light-emitting elements has a micro LED including a compound semiconductor crystal and a transparent portion arranged on the micro LED, and the light-emitting surface of the micro light-emitting element is an upper surface of the transparent portion.
13. The image display element according to claim 11, wherein a surface of a side wall constituting the wavelength conversion portion in a direction parallel to the light emitting surface is a surface inclined so as to open in a light emitting direction.
14. The image display element according to claim 12, wherein a surface of a side wall constituting the transparent portion in a direction parallel to the light emitting surface is a surface inclined so as to open in a light emitting direction.
15. An image display element according to claim 13, wherein a side wall of the wavelength conversion region in a direction parallel to the light emitting surface is covered with a highly reflective metal film.
16. An image display element according to claim 14, wherein a side wall of the transparent portion in a direction parallel to the light emitting surface is covered with a highly reflective metal film.
17. The image display element according to claim 11, wherein the wavelength converting region is disposed inside the partition wall, and the wavelength converting region and the microlens are sequentially laminated.
18. The image display element according to claim 11, wherein the reflection surface covers a periphery of the wavelength conversion portion in a direction parallel to the light emitting surface.
19. The image display element according to claim 1, wherein a height of the reflecting surface in a center line direction is equal to or less than a height of the microlens in the center line direction.
20. The image display element of claim 1, wherein the plurality of micro-light emitting elements are a plurality of quantum dot LEDs each having a quantum dot layer including quantum dots and emitting light by energizing the quantum dot layer.
21. The image display element of claim 1, wherein the plurality of micro-light emitting elements are a plurality of organic LEDs.
22. The image display element according to claim 9, wherein the first electrode is formed in a concave shape on a side opposite to the light exit surface side.
23. The image display element according to claim 11, wherein a plurality of dielectric multilayer films that reflect the excitation light and transmit the extended light of the wavelength are arranged on a light exit surface that emits the light of the microlens.
24. The image display element of claim 11, wherein the microlens comprises a filter material that absorbs the excitation light and transmits the extended light of the wavelength.
25. An image display element comprising a plurality of micro light emitting elements arranged in an array, comprising:
a drive circuit board including a drive circuit for supplying current to the plurality of micro light emitting elements and emitting light therefrom;
the plurality of micro light emitting elements;
a plurality of wavelength converting regions laminated on each of the plurality of micro light emitting elements, an
A plurality of partition walls disposed around the plurality of wavelength conversion portions in a direction parallel to the light emitting surfaces of the plurality of micro light emitting elements,
A plurality of the wavelength conversion portions extend the wavelength of excitation light of the plurality of micro light emitting elements,
the wavelength converting region is formed in a shape including a curved surface protruding in the light emitting direction,
the side of the partition wall facing the wavelength converting region is a reflecting surface that is inclined in such a manner as to be opened with respect to the light emission direction,
and the reflecting surface is not in contact with the surface of the wavelength converting region and reflects light emitted from the wavelength converting region in a direction along the front direction of the micro light emitting element,
at least a portion of the partition wall is at the same height in the light emission direction as a surface of the wavelength converting region forming a curved surface.
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| JP2019125201A JP7282620B2 (en) | 2019-07-04 | 2019-07-04 | image display element |
| JP2019-125201 | 2019-07-04 |
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| CN112185268A CN112185268A (en) | 2021-01-05 |
| CN112185268B true CN112185268B (en) | 2023-07-28 |
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| JP (1) | JP7282620B2 (en) |
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| US20210005583A1 (en) | 2021-01-07 |
| US11424225B2 (en) | 2022-08-23 |
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